Individual-level interventions to prevent cardiovascular disease (CVD) have been met with limited success in many minority communities, partly because they do not address the sociocultural context in which individuals live and make food and physical activity choices. Widening our inquiry beyond the individual, to the larger social drivers can provide key insights into how social influences can be leveraged in interpersonal and community-level interventions to engage at-risk communities. Social networks influence health via many mechanisms: social influence and control; establishment of health beliefs and normative behaviors; feelings of shared identity and belonging; and provision of support. Social influences are key determinants of health; yet social network analysis has rarely been used to examine links between social networks and health in minorities. The Mediators of Atherosclerosis in South Asians Living in American (MASALA) study is the first population-based cohort of South Asians (SAs) in the United States and is a substantial investment by the National Institutes of Health to understand the CVD disparities in the rapidly growing SA population. We propose to leverage that investment to investigate social network structures and sociocultural drivers of CVD risk factors in the MASALA cohort. Social relationships an especially important influence on SAs health behaviors because 90 percent are immigrants who believe kinship and family are paramount with emphasis on collectivism, social control, and maintenance of group identity. Our data from the MASALA study show that SAs have the highest prevalence of diabetes, an important CVD risk factor, and the lowest levels of physical activity compared to Whites, Blacks, Hispanics, and Chinese in the Multiethnic Study of Atherosclerosis. We also find that sociocultural influences may be partly driving these disparities and that individual-level prevention efforts may not be as effective in the tightly-knit, family-oriented SA community. In the proposed ancillary project, the multidisciplinary research team will utilize quantitative social network methods to: 1) Uncover the unmeasured sociocultural drivers of variance in proximal CVD risk factors (body mass index, waist circumference, diet and physical activity behaviors); and qualitative methods to: 2) Investigate the meaning, significance, and function of SAs' social networks with respect to how they influence food and physical activity preferences and constraints. Qualitative interviews will provide greater context to the quantitative findings and elucidate mutable avenues for future intervention. Our team, with expertise in CVD prevention and nutritional epidemiology, sociocultural determinants of health, and social network analysis are well-poised to conduct this mixed methods research. The proposed research addresses critical gaps in CVD prevention research: understanding the influence of social networks on CVD risk and how these influences can be leveraged to improve the cardiovascular health of immigrant and minority communities.